Long-term objectives Based on preliminary studies on Israeli volunteers, it was concluded that only 60% of the population revaccinated against Smallpox reacted to the vaccine, of whom only 10% did so at very high titers. The aim of this R&D project is to develop and produce a high-titer, small volume Vaccinia Immune Globulin (HT-VIG) as an effective countermeasure to Smallpox and the side effects of the Vaccinia vaccine, which can be administered by intra-muscular or intra-venous mutes, including self-injection. The resulting product will be at least ten times more concentrated than existing VIG preparations that are based on immunoglobulin preparations from non-selected, pooled plasma, and it will have greater efficacy. Importantly, it will be a safe and effective prophylactic treatment against Smallpox for people excluded from the Vaccinia vaccination due to immunodeficiency or other risk factors. Given the heightened risk of a Smallpox outbreak due to bio-terrorism, the project's importance and health relevance cannot be underestimated. Specific Aims Omrix' existing ELISA test will be validated, establishing the correlation between it and the standard Vaccinia neutralization assay. The validated ELISA test will be used to determine the level of anti-Vaccinia immunoglobulins in human plasma samples. Following that, the ELISA will be used to screen USA plasma derived from re-vaccinated donors and select high titer anti Vaccinia plasma samples. These samples will be used to produce a limited number of batches of High-Titer VIG, which will then be characterized by use of the ELISA test and the standard Vaccinia Neutralization Bioassay. Development of a concentrated HT-VIG formulation for either small volume IV or IM administration. Research Design & Methods As well as employing standard operating procedures for plasma collection and fractionation, innovative methodology will be employed in two areas of the program: 1) a new validated ELISA screening test will enable selection of very high titer plasma samples resulting in a high potency, small volume HT-VIG product; 2) the development of the HT-VIG product will include the new viral removal steps developed by Omrix, such as nano-filtration and solvent detergent treatment, which exhibit high margins of viral inactivation of all known viruses, including Parvo-viruses.